1. Field of the Invention
The present invention relates to a semiconductor device having a semiconductor nonvolatile memory element, and more particularly a semiconductor device having a semiconductor nonvolatile memory element formed with thin films and a transistor. Further, the present invention relates to a semiconductor device such as an ID chip, a CPU, or a system LSI, having a semiconductor nonvolatile memory element.
2. Related Art
An EEPROM (Electrically Erasable and Programmable Read Only Memory) or a flash memory is known as a typical memory of a semiconductor nonvolatile memory. Since these memories are nonvolatile, data is not lost even when power source is turned off in contrast with a DRAM (Dynamic Random Access Memory) or SRAM (Static RAM), each of which is volatile. In the case of comparing with a magnetic disk that is another typical nonvolatile memory, the EEPROM or the flash memory has advantages in integration density, impact resistance, power consumption, write/read speed, and the like (for example, see Japanese Unexamined Patent Publication No. 2003-204000).
A nonvolatile memory formed by using a single crystalline semiconductor substrate has been put into practical use and offered in markets. Especially a nonvolatile memory having large memory capacitance, that is, high integration density is widely used.
On the other hand, a semiconductor device as typified by an ID chip capable of wireless sending and receiving data such as identification information has been put into practical use in various fields, and has been expected to increase in trade as a new form information-communication terminal. The ID chip is referred to as a wireless tag, an RFID (Radio Frequency Identification) tag, or an IC tag. An ID chip that has an antenna and an integrated circuit formed by using a semiconductor substrate is about to be put into practical use at present.
Illegal rewrite of identification information of the ID chip can be prevented by forming a nonvolatile memory which data is impossible to be rewritten in an integrated circuit in the ID chip.
However, it is required to manufacture a vast number of ID chips available for human, animals, merchandise, paper money, and the like at extremely low costs as non-contact type or contact type ID chips are spread, and so it has been required to realize a structure and a manufacturing process of an ID chip capable of being mass-produced at low costs.
In the existing circumstances, a method of forming a plurality of integrated circuits and dividing the plurality of integrated circuits by back-grind of the silicon wafer is used to manufacture an ID chip. However, the problem of high manufacturing cost cannot be avoided since the silicon wafer is removed by back-grind even though silicon wafers are expensive. Since the integrated circuit formed by the silicon wafer is thick, irregularities are generated on a surface of a product container in the case of mounting the integrated circuit to the product container itself, and so latitude of design selection is limited.
A semiconductor device as typified by a CPU or a system LSI is required to be mounted in a limited capacity of an electric appliance. Accordingly, it has been required to reduce a thickness of an integrated circuit of the semiconductor device in order to realize reduction in size and weight.